1. Field of the Invention
The present invention relates to safety syringes having retractable needle cannulas.
2. Background of the Related Art
There are safety syringe devices of various designs that will allow the needle to retract into either the barrel or plunger of the syringe. Some of these devices are described in U.S. Pat. No. 4,973,316 (Dysarz), U.S. Pat. No. 4,978,343 (Dysarz), U.S. Pat. No. 5,180,369 (Dysarz), U.S. Pat. No. 5,267,961 (Shaw), U.S. Pat. No. 5,019,044 (Tsao), U.S. Pat. No. 5,084,018 (Tsao), U.S. Pat. No. 5,385,551 (Shaw), U.S. Pat. No. 5,389,076 (Shaw), U.S. Pat. No. 5,201,710 (Caselli), U.S. Pat. No. 6,010,486 (Carteret al), U.S. Pat. No. 5,120,310 (Shaw), U.S. Pat. No. 5,188,613 (Shaw), and U.S. Pat. No. 6,033,385 (Liu). Although these devices reduce accidental needle sticks, an operator of the devices may cause the needle to prematurely retract during the process of filling the syringe (aspiration) or while medication is being injected into a body.
For example, during aspiration the plunger is pushed in as far as it will go into the syringe (just prior to pulling the plunger back to draw the medication or other fluid from a container or body) such that the plunger may trigger the retraction mechanism and cause the needle to prematurely retract, thereby resulting in the loss of the needle cannula, an expensive syringe, more expensive medication, and even more expensive labor (doctor, nurse, etc). Usually the operator of the device does not know at what precise point to stop pressing the plunger into the syringe prior to or during aspiration.
Other types of safety syringes are devices with a sleeve or a sheath that will cover the needle after it has been used. To aspirate or fill this type of syringe, one must sight the medication through two layers of plastic or glass; if a clear fluid is being drawn into the syringe it may not be possible to see the necessary dosage.
Most of the devices mentioned above are not modular wherein a needle cannula of any size may be used with a syringe of any size. Rather, the needle cannula is made as part of the syringe and the two are not interchangeable with other needle cannulas or syringes of different sizes or capacities. Other safety syringes that are modular, include the devices disclosed in U.S. Pat. No. 5,891,093 (Dysarz), U.S. Pat. No. 6,016,595 (Dysarz), U.S. Pat. No. 5,935,113 (Dysarz), and U.S. Pat. No. 6,010,486 (Carter et al).
However, there remains a need for a safety syringe that is modular, wherein various needle cannulas are interchangeable with various syringes. It would be desirable if the modular safety syringe were compatible with existing inventories of needles. Furthermore, there remains a need for a safety syringe with a positive latching device that will remain latched during aspiration and that can only be released with a positive release means when the user desires to release the needle latching devise.
The present invention provides a retractable safety syringe module, comprising a syringe housing having a syringe barrel and a retraction trunk formed together at a distal end of the syringe housing to form an annular chamber between the syringe barrel and the retraction trunk, wherein the distal end of the retraction trunk forms a sealing collar having a port in fluid communication with the annular chamber. The syringe module also comprises an annular plunger extending through a proximal end of the annular chamber, the annular plunger having a sliding gasket formed along the distal end of the annular plunger for sealing against the interior of the annular chamber. A biased needle cannula carriage is releasably secured against the sealing collar, the biased needle cannula carriage having a connector for selectively receiving a needle cannula and a passage providing fluid communication between the sealing collar port and the connector. A retaining member releasably secures the biased needle cannula carriage against the sealing collar.
The needle cannula carriage is biased in the proximal direction into the retraction trunk and has dimensions allowing it to retract into the retraction trunk without restriction. A needle cannula is selectively and/or disconnectably connectable to the carriage, preferably by a connector selected from screw threads, luer-loks, or snap-on fittings. An exterior surface of the carriage mates with the interior surface of the sealing collar, wherein the mating surfaces are preferably selected from steps and cones. A retaining member, such as a carriage stop arm, is provided to secure the carriage base against the sealing collar.
One aspect of the invention provides a kit of components for assembling safety syringes, comprising two or more safety syringe modules, optionally having different diameters, and two or more needle cannula modules, optionally having different sizes. Each safety syringe module and each needle cannula module are provided in accordance with any embodiment described herein. The connectors in any of the two or more safety syringe modules are sealably securable to any of the connectors in the two or more needle cannula modules to provide fluid communication between the needle cannula and the passage in the carriage base. Specifically, the connectors are preferably selected from threads, luer-loks, snap-on fittings, or slip on fittings.